1. Technical Field
The solution according to one or more embodiments of the present disclosure relates to the electronics field. More specifically, such solution relates to electronic devices for power applications.
2. Description of the Related Art
Each electronic device typically comprises a chip—for example, of semiconductor material—on which components and/or electronic circuits are integrated, and a package in which the chip is embedded for protecting it and for allowing access to terminals thereof. The chip of an electronic device for power applications (e.g., AC adapters), hereinafter simply referred to as power device, typically integrates a power component, such as a power transistor of the MOS or BJT type, or a power diode.
The package of a power device comprises an insulating body having exposed leads, which are electrically connected to corresponding terminals of the chips (e.g., by a “wire-bonding” technique). The leads of the package are used for connecting the same (and thus the corresponding terminals of the chips) to external circuits. For such purpose, the power device is usually mounted on a printed circuit board (PCB), for example by surface mounting technology (or SMT), wherein the leads of the package comprise pads that are first fixed to corresponding conductive tracks of the PCB by a slight pressure (pick and place), and then reflow-welded on the same, or by through-hole technology (or THT), wherein the leads of the package comprise electrodes that are inserted into through-holes of the PCB and back-welded on it.
Semiconductors do not perform well at elevated temperature. However, since the chip of a power device is affected by high voltages and/or currents, it tends to heat up. Therefore, the power devices are cooled by removing that heat continuously. For this reason, heatsinks are provided to remove heat from the power device (and particularly, from the chip) by conducting it to the external environment through the package. Making reference in particular to a power device provided with electrodes, the heatsink is typically a metallic plate adapted to contact the package of the power device when the latter is mounted on the PCB. In order to remove heat from the power device in an efficient way, so as to keep the temperature thereof at safe levels, the package of the power device should be attached to the heatsink in such a way that a sufficiently large surface portion of the insulating body is in direct contact with the heatsink itself.
According to a solution known in the art, the package of the power device is configured to be fastened to the heatsink by means of an insertable fastener, such as for example a screw, configured to go through the insulating body. For this purpose, the insulating body of the package, as well as the heatsink, are provided with corresponding through-holes adapted to receive the screw. The position of the holes is such that, when the power device is mounted to the PCB (i.e., when the electrodes thereof are inserted into through-holes of the PCB), the hole on the package is aligned with the hole on the heatsink; having mounted the power device on the PCB, the power device is then firmly fastened to the heatsink by inserting the screw inside the two aligned holes.
The Applicant has observed that a solution of this type is not suitable for all the applications affected by size constraints, such as for example the AC adapters, whose size imposed by the actual demands is becoming more and more reduced. Indeed, with the abovementioned solution, the insulating body of each power device included in an AC adapter has to include a dedicated fixing portion in which the hole for receiving the insertable fastener is located. In order to correctly allow the passage of the insertable fastener through the hole avoiding any risk of damaging the chip wherein the power component is integrated, such fixing portion of the insulating body has to be located apart from the location of the chip. For this reason, the fixing portion is typically an additional protruding portion of the insulating body, whose presence sensibly increases the whole size of the power device.